URL Shortener Service

How to Run the Project Locally

1. Make sure you have Java 21, Maven, Docker, and MySQL installed.
2. Start MySQL and create the database:

   mysql -u root -p
   CREATE DATABASE shortener_db;

3. Update src/main/resources/application.properties with your MySQL credentials if needed.
4. Build and run the app:

   mvn clean package
   java -jar target/*.jar

5. Or run with Docker:

   docker build -t shortener-backend .
   docker run -p 8080:8080 --env SPRING_DATASOURCE_URL=jdbc:mysql://host.docker.internal:3306/shortener_db --env SPRING_DATASOURCE_USERNAME=root --env SPRING_DATASOURCE_PASSWORD=YOUR_PASSWORD shortener-backend

Example API Usage (curl)

• Shorten a URL:

  curl -X POST http://localhost:8080/api/shorten -H "Content-Type: application/json" -d '{"url":"https://example.com"}'
  # Response: { "shortCode": "abc123" }

• Redirect:

  curl -v http://localhost:8080/abc123
  # 302 redirect to https://example.com

• Analytics:

  curl http://localhost:8080/api/analytics/abc123
  # Response: { "originalUrl": ..., "shortCode": ..., "redirectCount": ..., "createdAt": ... }

How the CI/CD Works

• GitHub Actions workflow runs on every push/PR to main.
• Steps: linter (Checkstyle), unit tests, build JAR, build & push Docker image to Docker Hub.
• Uses MySQL service for integration tests in CI.

How Deployment Works

• Docker image is deployed to Google Cloud Run.
• Cloud Run connects to Cloud SQL (MySQL) using the Cloud SQL Proxy.
• Environment variables for DB connection are set in Cloud Run.
• Service listens on the port provided by the PORT environment variable.

Time Breakdown

• Core API & DB logic: ~4 hours
• Dockerization: ~30 minutes
• CI/CD setup: ~4 hour
• Cloud Run deployment: ~2 hour
• Debugging & edge cases: ~3 hour

Tradeoffs / Shortcuts

• Used reflection for unit tests to avoid Spring context loading in CI.
• Did not implement full integration tests (could be added for end-to-end validation).
• Used basic URL validation (Java URL class) instead of a more robust validator.
• Secrets for DB and Docker Hub are managed via GitHub Actions and Cloud Run env vars.
• Some test cases and debugging steps were generated or assisted by OpenAI's ChatGPT.